Positron emission tomography (PET) has been widely used in medicine for diagnosis and other purposes. An object, such as a patient, may be scanned with a PET system to obtain PET datasets. Precise image reconstruction may be based on precise datasets reflecting the actual condition. Precise datasets may depend on the detector and data processing module in a good working condition. Method for evaluating and calibrating the photodetector and time information have been developed.
Generally, in medical imaging, consistency of the scanners is of great importance. One of the most significant challenges in maintaining the stability of a scanner in nuclear imaging is keeping a photodetector in a precise working condition. Output of a photodetector is known to drift over time, as a result of usage and temperature. For technicians, an evaluation of the photodetector before or during the detecting may be necessary, traditional calibration method may introduce extraneous radiation source.
Datasets may be processed after the detecting procedure of the photodetector. Time information of each electrical signal may be extracted precisely during the data processing. However, due to the nonlinearity of the delay-line, the time information may be sometimes calculated erroneously. Thus, a calibration during the extraction of time information may be indispensable.